There's actually a ton of analog stuff to listen to on the Gold Simulcast, it just happens most of it is not law enforcement or fire/ems related. There are a few good ones, especially the Bexar County Sheriff's Open talkgroups(1042, 1044, 1046). Also, occasionally ProVoice talkgroups will come across with analog traffic, though I wouldn't say it would be worth it to program in all these for your short visit.
You should also program in the Blue Simulcast, though this is reserved for SAPD, the Park Police also operate on this but in analog(they have 3 or 4 talkgroups). The Park Police are responsible for patrolling the river walk and some associated areas so if that's where you're going to be you may want to plug them in, though they're not always very busy.
With the 396 though you'll need the latest firmware update to be able to trunk track ESK EDACS systems. The scanner just ignores ProVoice; its the ESK that prevents most scanners from following. If you have any questions about listening to the simulcasts, I pretty much have them on everyday I'm here in SA and hear enough law enforcement activities and other interesting things to keep me from deleting them to clear up room on my scanner.
Also add in TABC Car-to-Car frequency 154.905 (forgot the CT). I hear them on their mobiles more often; greater range I suppose.